SOLAR PHOTO VOLTAIC (PV

9.31 Photo Voltaic Solar converts sunlight into DC (Direct Current) electricity. To use this electricity within a household an inverter is required to produce AC (Alternating Current) electricity.

9.32 Solar panels deliver power during daylight hours; the stronger the light (not heat), the greater the power produced. As well as daily variability, power produced varies during the year due to the variation in light intensity and angle of the sun. Solar PV is used in small domestic rooftop installations, typically 4kWp (peak), or in large solar farms, beyond 70MW with approved proposals for installations up to 350MW. [178]

Solar energy generation is seasonal

Solar power growth has been significantly affected by subsidies. By 2021, there was 14GW of Solar generating 12,000GWh per annum. The Government plans for 70GW of solar by 2030, generating around 60,000GWh per annum.

9.33 The UK’s largest solar farm will be the 350MW Cleve Hill Solar Park in Kent. It is expected to produce 264GWh annually, lowering CO2 emissions by 68,000 tonnes a year. Around 57% of the total solar capacity relates to large ground-mounted installations. [179]

Solar Farm at Ernesettle, Plymouth (Photo Malcolm Teague)

9.34 Most solar installations in the UK are installed to deliver the highest peak power, meaning south facing panels at the optimum elevation angle. However, to extend the generation time and better cover the seasons, east-west installations are now being installed and are being backed by Battery Energy Storage Systems BESS.

[180]

9.35 Typical solar panel efficiency is between 21 and 22.5%. This efficiency affects the size of the panel as it is a ratio of sunlight received versus power delivered. Unlike fossil fuel power generation, this is not really a ratio that affects the cost of use although it will impact installation costs. Panel sizes have increased over the past decade. This is particularly beneficial for the installation costs of large solar farms. [181] 9.36 Solar PV sites can easily be returned to their original, or better, state at the end of their lives. National planning policy in England and Wales requires a solar farm development to deliver a biodiversity net gain and greater biodiversity resilience. [182 183] Solar Farm sites can be a haven for biodiversity. [184], can be integrated into agricultural settings, shielding plants growing beneath them from extreme weather whilst allowing sheep to graze beneath them. [185 186 187] 9.37 The National Planning Policy Framework expresses a preference for large scale ground mounted solar PV systems to be sited on agricultural land graded 3b, 4 and 5. [188] DEFRA has recently indicated it is considering a solar ban on lower quality English farmland. [189]

9.38 Floating solar farms can also be installed on reservoirs. An analysis of the UK’s top ten reservoirs indicates the potential for up to 6.8GWp, about half of the 2022 cumulative installation. Potential concerns include seasonal fluctuation of water level affecting the number of panels that can be installed; grid connection availability; and higher upfront and maintenance costs. [190]

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9.39 For Plymouth, planning permission for a community owned solar farm on the old landfill site at Chelson Meadows has now been granted. The proposal is for a 13.2MW solar array backed by energy storage. The solar farm should generate enough energy to power 3,800 homes (~3.3% of Plymouth’s housing stock). The scheme is supported by the Rural Community Energy Fund Programme. [191] 9.40 A recent innovation has been to site solar farms offshore in and around wind farms thereby improving the power output for a given area. For countries such as the Netherlands, land space is very limited whilst sea space is comparatively open. Tests have proven the ability for floating solar to withstand the rigours of the offshore environment. [192 193]

9.41 Domestic rooftop solar can be incorporated on build or as a retrofit. Environmental impact of solar [194 195] 9.42 The environmental impact of solar PV during operation is minimal in comparison with other technologies for producing energy. Panels are easily removed if no longer required.

9.43 When considering the manufacture and disposal phases, hazardous material, water resource pollution, and emissions of air pollutants during manufacture should be considered. Using less material per kWh and improving the carbon emissions of the country of manufacture’s electricity grid will lead to improvements. The key issues concern quartz mining and refining silicon which entails the use of silicon tetrachloride. Some manufacturers of solar PV recycle the silicon tetrachloride and some discard it. When exposed to water, silicon tetrachloride produces hydrochloric acid, acidifying the soil and producing toxic fumes. Hydrofluoric and sulfuric acids are used when cleaning silicon wafers.

9.44 Solar farms do take a lot of land area (~half a square kilometre (10 acres) per MWp) but done sympathetically, biodiversity does not seem to be negatively affected. Clarkson & Woods (ecological consultants) in research conducted in 2015 concluded: solar farms had greater botanical diversity, greater invertebrate abundance, greater diversity of birds - and that solar farms are of particular benefit for bird conservation. [196 197]. Bat activity may be lower within ground mounted solar arrays. Bats are also affected by inroof mounted solar panels as they change the background temperature of the roof. [198] 9.45 Professional and independent consultants, BSC-Ecology, having done a literature review in 2019 on the “Potential ecological impact of ground-mounted photovoltaic solar panels’ concluded: “From the body of research reviewed, it is likely that the majority of concerns that have been discussed in the media are not well founded, or are based on scientific experiments that were not specifically designed to evaluate ecological impacts of ground mounted solar PV sites”. [199]